A great variety of ink jet printing technologies are known in the patent literature. Among these technologies is the use of inks of the same color but of different densities in multiple jets of an ink jet printer. The following U.S. Pat. Nos. are believed to represent the state of the art at the time that the present invention was made: 4,367,482; 4,494,128; 4,560,997; 4,604,654; 4,635,078; 4,672,432; 4,686,538; 4,695,846; 4,713,746; 4,714,964; 4,855,753; 4,860,026; 4,952,942; 4,963,882; 4,967,203; 4,999,646; 5,091,734; 5,111,302 and 5,142,374.
Dot on dot ink jet printing is known in the patent literature inter alia from U.S. Pat. Nos. 4,620,196 and 4,851,860.